title: Scanning electron microscopic imaging of surface effects in desorption and nano-desorption electrospray ionization.
abstract: Scanning electron microscopy was used to investigate rivulets that are formed on the analyzed surface during desorption electrospray ionization (DESI) experiment. Ferromagnetic nanoparticles added to the spray solvent in a form of colloid solution functioned as an additional surface probe. The existence of the rivulets was confirmed on glass and newly demonstrated on two different types of porous polytetrafluoroethylene (PTFE). The results show that in standard DESI set-up the rivulets are arranged into very regular shapes. Same rivulets were obtained in DESI experiments without high voltage on the sprayer. However, no such rivulets or any other regular patterns were found on a surface in nano-DESI (nanospray DESI without the carrier nebulizing gas) experiments. This indicates that symmetrical rivulets are created by the hydrodynamical rather than electrostatic forces. It was also demonstrated that blocking the rivulets by a simple physical barrier did not influence known surface charging effects.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v. v. i., Flemingovo nám. 2, 16610 Prague 6, Czech Republic.
authors.forename: Filip
authors.initials: F
authors.lastname: Kaftan
authors.forename: Olga
authors.initials: O
authors.lastname: Kofroňová
authors.forename: Oldřich
authors.initials: O
authors.lastname: Benada
authors.forename: Karel
authors.initials: K
authors.lastname: Lemr
authors.forename: Vladimír
authors.initials: V
authors.lastname: Havlíček
authors.forename: Josef
authors.initials: J
authors.lastname: Cvačka
authors.forename: Michael
authors.initials: M
authors.lastname: Volný
mesh_terms: D005898:Glass / Q000737:chemistry; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D011138:Polytetrafluoroethylene / Q000737:chemistry; D012235:Rhodamines / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D055672:Static Electricity
chemical_list: D058185:Magnetite Nanoparticles; D012235:Rhodamines; D011138:Polytetrafluoroethylene; C029773:rhodamine B